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1.
Riassunto Sono state studiate le variazioni del rapporto tra l'N proteico e non proteico in segmenti rigeneranti, nucleati ed anucleati, diAcetabul. medit. I risultati ottenuti hanno dimostrato che il predetto rapporto aumenta in entrambi i segmenti il primo giorno dopo l'operazione. Nei giorni seguenti esso diminuisce in entrambi i segmenti, ma più sensibilmente in quelli anucleati, nei quali va al di sotto del valore medio delle alghe normali già dopo il 3°–4° giorno.  相似文献   

2.
Riassunto È stato studiato il contenuto di ATP nella cartilagine epifisaria di giovani ratti diabetici per allossana. Il deficit insulinico da diabete allossanico provoca, oltre ad arresto dell'accrescimento scheletrico, una diminuzione della concentrazione di ATP nella cartilagine di coniugazione. Il significato biologico di questo risultato è messo in relazione col meccanismo d'azione dell'insulina e con l'importanza dell'ATP nel processo di ossificazione encondrale.  相似文献   

3.
Riassunto Studiando il meccanismo biochimico con cui la insulina controlla il processo di osteogenesi, si è stabilito che in condizioni di deficit insulinico (diabete allossanico) esiste nel ratto accanto ad un arresto dell'accrescimento scheletrico, una notevole riduzione dell'attività cocarbossilasica nella cartilagine epifisaria. Si conclude che nella cartilagine di coniugazione ATP e cocarbossilasi sono strettamente interdipendenti per quanto riguarda la loro biosintesi; inoltre che il loro normale metabolismo è indispensabile al normale svolgersi del processo di osteogenesi.  相似文献   

4.
This paper analyses the revival of Pliny's Naturalis historia within the scientific culture of the late eighteenth and early nineteenth centuries, focusing on a French effort to produce an edition with annotations by scientists and scholars. Between the Renaissance and the early eighteenth century, the Naturalis historia had declined in scientific importance. Increasingly, it was relegated to the humanities, as we demonstrate with a review of editions. For a variety of reasons, however, scientific interest in the Naturalis historia grew in the second half of the eighteenth century. Epitomizing this interest was a plan for a scientifically annotated, Latin-French edition of the Naturalis historia. Initially coordinated by the French governmental minister Malesherbes in the 1750s, the edition was imperfectly realized by Poinsinet a few decades later. It was intended to rival two of the period's other distinguished multi-volume books of knowledge, Diderot and D'Alembert's Encyclopédie and Buffon's Histoire naturelle, to which we compare it. Besides narrating the scientific revival of the Historia naturalis during this period, we examine its causes and the factors contributing to its end in the first half of the nineteenth century.  相似文献   

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Zusammenfassung Vom ektodermalen Proctodaeum wächst ein kleiner Divertikel dem Vornierengang entgegen und vereinigt sich mit dessen kaudalem Ende. Einen weiteren Anteil hat das Proctodaeum an der Bildung des Vornierenganges nicht. Zugleich mit dem Proctodaeum invaginiert Material für den Mesonephros, das sich in Zellgruppen entlang dem hinteren Ende des Vornierenganges lagert.  相似文献   

7.
This Special Issue Hermann Weyl and the Philosophy of the ‘New Physics’ has two main objectives: first, to shed fresh light on the relevance of Weyl's work for modern physics and, second, to evaluate the importance of Weyl's work and ideas for contemporary philosophy of physics. Regarding the first objective, this Special Issue emphasizes aspects of Weyl's work (e.g. his work on spinors in n dimensions) whose importance has recently been emerging in research fields across both mathematical and experimental physics, as well as in the history and philosophy of physics. Regarding the second objective, this Special Issue addresses the relevance of Weyl's ideas regarding important open problems in the philosophy of physics, such as the problem of characterizing scientific objectivity and the problem of providing a satisfactory interpretation of fundamental symmetries in gauge theories and quantum mechanics. In this Introduction, we sketch the state of the art in Weyl studies and we summarize the content of the contributions to the present volume.  相似文献   

8.
Periodicity in predatory activity was observed in overwintered females ofTyphlodromus pyri Scheuten (Acari: Phytoseiidae). Chronobiometrical analysis revealed that an approximately circabiseptan (about-14-day) rhythm is statistically significant, with a striking depression around the full moon.  相似文献   

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This paper explores the history of a unique assemblage of researchers in the geodetic and allied sciences organised at Ohio State University (OSU) in 1947 at the beginning of the Cold War. From about 1950 to 1970, the OSU geodetic sciences group was the most significant group of geodetic researchers in the world. Funded almost entirely by military and intelligence agencies, they pioneered the technologies, organised the research initiatives, ordered the data sets, and trained the generation of geodesists who eventually created the Cold War Figure of the Earth to both prosecute and prevent global nuclear war. They devised elaborate mechanisms to pursue in secrecy and isolation research that had hitherto been performed collaboratively and globally. They invented methods to maintain professional associations and protocols, both to distribute—and disguise—the fruits of their geodetic research. In accomplishing this, their work also undermined the basic hypothesis of isostasy that had been foundational to geodesy for the previous century.Fundamental progress in the geosciences and military and intelligence directives were inextricably linked during the Cold War, although the extent of their convergence has been masked by the security protocols organised to disguise it. With the declassification of key programmes underway, it is now both possible and necessary to substantially revise the history of Cold War-era geosciences and their associated technologies.  相似文献   

11.
Summary Formulae are fitted to the different sets of values, given by the translators, for the equation of centre for the motion of the moon according to the Romaka Siddhnta, as found in the Pañcasiddhntik of Varha Mihira.  相似文献   

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Zusammenfassung Der Gehalt an Ribonukleinsäure und Desoxyribonukleinsäure der normalen Tritoneier (T.palmatus) und der letalen Bastardeier (T.palmatus ×S.atra ) wurde im Morula-, Blastula- und Gastrulastadium mikrophotometriert. Bei normalen Eiern wurde keine wesentliche Änderung des Ribonukleinsäuregehaltes festgestellt. Hingegen nahm die Konzentration der Desoxyribonukleinsäure von der späten Morula bis zur mittleren Blastula deutlich zu und zeigte dann bis zum Gastrulastadium nur geringe Zunahme.Während der Furchung ist der Nukleinsäurengehalt der Bastardeier normal. Die mittlere Blastula (kritische Phase: etwa 24 h bei 18°C) ist aber gegenüber den Kontrollkeimen bedeutend ärmer an beiden Nukleinsäuren. Eine leichte Zunahme der Desoxyribonukleinsäure vor der kritischen Phase, ohne jedoch die Konzentration eines normalen Eies zu erreichen, wurde beobachtet. Die entwicklungsphysiologische Deutung der vorliegenden Befunde wird diskutiert.

This work was supported by a grant from the Karl-Hescheler-Stiftung.  相似文献   

14.
Zusammenfassung Gibt man L(+)-Lysin--15N oder in allen Stellungen mit14C markiertes L(+)-Lysin zu keimfreien Kulturen von abgeschnittenen Wurzeln vonNicotiana tabacum, so erzeugen die Wurzeln Nikotin, welches kleine Mengen15N oder14C enthält. Ferner enthält das Nikotin mehr15N oder14C im Pyrrolidinring als im Pyridinring. Lysin liegt daher nicht auf dem direkten biogenetischen Weg zum Nikotin.

Research performed under the auspices of the United States Atomic Energy Commission.  相似文献   

15.
Theories of familial, racial, and national degeneration in the late nineteenth and early twentieth centuries have been explored by historians in the context of social and moral pathology. At the same time nerve degeneration was studied in the post mortem room and in the laboratory but links to the broader ideology of degeneration have not been investigated by scholars. This paper joins these domains by examining the concept of Wallerian degeneration. It argues that various discourses—including those of the laboratory scientist, the clinician, and the social theorist—employed the term degeneration, and these discourses frequently overlapped demonstrating that degeneration was a ubiquitous fact of Victorian and Edwardian nature.  相似文献   

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Summary During the conversion of cholesterol into 3 -hydroxymethyl-A-nor-5-cholestane by the spongeAxinella verrucosa, the carbon-3 of this latter originate from carbon-4 of cholesterol. Cholestanol moreover does not seem an intermediate in this conversion.  相似文献   

18.
In this paper the relation between the standard probabilistic characterization of the common cause (used for the derivation of the Bell inequalities) and Bell׳s notion of local causality will be investigated in the isotone net framework borrowed from algebraic quantum field theory. The logical role of two components in Bell׳s definition will be scrutinized; namely that the common cause is localized in the intersection of the past of the correlated events; and that it provides a complete specification of the ‘beables’ of this intersection.  相似文献   

19.
Over many years, Aharonov and co-authors have proposed a new interpretation of quantum mechanics: the two-time interpretation. This interpretation assigns two wavefunctions to a system, one of which propagates forwards in time and the other backwards. In this paper, I argue that this interpretation does not solve the measurement problem. In addition, I argue that it is neither necessary nor sufficient to attribute causal power to the backwards-evolving wavefunction Φ| and thus its existence should be denied, contra the two-time interpretation. Finally, I follow Vaidman in giving an epistemological reading of Φ|.  相似文献   

20.
Résumé L'examen histochimique des spermatides du bouc et du buffle montre que le «complexe de Golgi» des auteurs comprend l'idiosome constitué par des protéides et des lipidoprotéides, les bâtonnets et granules constitués par des phospholipides et peut-être des protéides et enfin les vacuoles.  相似文献   

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